Avoid swagger validation when browsing /swagger

Impact on the user
Privacy issues

Steps to reproduce

• Login to PMM using an address other that 127.0.0.1 or localhost
• Navigate to /swagger
• Scroll down to the bottom to view validation status

Actual result
Online validation is automatically attempted each time the swagger documentation is viewed by the user.

Expected Result
Online validation does not occurr when viewing the swagger documentation.

Workaround

• Enter the PMM container/server
• cd /usr/share/pmm-server/swagger/
• sed -i 's;validatorUrl:"https://validator.swagger.io/validator";validatorUrl:"";g' *

Details
The swagger documentation automatically sends the user's PMM server address to a remote validation service:

By default, Swagger UI attempts to validate specs against swagger.io's online validator. You can use this parameter to set a different validator URL, for example for locally deployed validators (Validator Badge). Setting it to either none, 127.0.0.1 or localhost will disable validation.

https://swagger.io/docs/open-source-tools/swagger-ui/usage/configuration/#network